Machines for compression molding closure shells typically include a turret or carousel that rotates around a vertical axis. A plurality of molds around the periphery of the carousel include male and female mold sections that are aligned along vertical axes parallel to the axis of rotation. Cams drive one or both of the mold sections of each pair between an open spaced-apart position, in which a molded part is stripped from the male mold section and a charge of plastic material is placed in the female mold section, and a closed position in which the male and female mold sections are brought together to compression mold the charge to form the shell. U.S. patents that illustrate machines of this type for compression molding plastic closure shells include U.S. Pat. Nos. 5,670,100, 5,989,007, 6,074,583 and 6,478,568.
There are applications in which it is desirable to provide an opening in the base wall of the closure shell. For example, U.S. 2004/0108294A1 discloses a plastic closure that includes a shell having a base wall with a central opening and a skirt with at least one internal thread or bead for securing the closure to a container finish. A plastic disk is retained within the shell parallel to but spaced from the closure base wall. One or more axially extending spacer elements on the disk engage the undersurface of the closure base wall and space the disk from the base wall of the shell. A resilient liner is disposed on the underside of the disk for sealing engagement with the container finish. Following application of the closure to a container finish, fluid may be directed through the opening in the closure base wall, between the disk and the undersurface of the base wall, past the spacer elements, and then between the closure skirt and the container finish to flush debris or the like from between the closure shell and the disk and finish. Another example would be a closure shell having an opening to receive a dispensing valve or the like. In compression molding closure shells of this type, the shell may be fabricated with a disk in the base wall, which is removed in a post-molding operation to provide the desired opening in the base wall of the shell. U. S. Pat. No 6,673,295 discloses a closure shell and a method of manufacture of this type. A general object of the present disclosure, in accordance with one aspect of the disclosure, is to provide a machine and a method for compression molding a closure shell having a base wall with an opening, in which the disk is removed from the closure shell within the compression mold, eliminating the need for a post-molding operation to remove the disk from the shell.